Ignition distributor for internal combustion engines of the type in which spark advance is dependent



27, 1968 HIROMU SHIGA ETAL 3,

IGNITION DISTRIBUTOR FOR INTERNAL COMBUSTION ENGINES OF THE TYPE IN WHICH SPARK ADVANCE IS DEPENDENT Filed Aug. 4, 1966 2 Sheets-Sheet 1 1 Prior an 9M NIM 5 F 7. 1968 HIROMU SHIGA ETAL 3,371,159

IGNITION DISTRIBUTOR FOR INTERNAL COMBUSTION ENGINES OF THE TYPE IN WHICH SPARK ADVANCE Is DEPENDENT Filed Aug. 4, 1966 2 Sheets-Sheet 2 United States Patent 3,371,169 IGNITION DISTRIBUTOR FOR INTERNAL COM- BUSTION ENGINES OF THE TYPE IN WHICH SPARK ADVANCE IS DEPENDENT Hiromu Shiga and Akio Kakiuchi, Nagoya shi, Japan, as- ;ignors t0 Nippon Denso Company Ltd., Kariya shi,

apan

Filed Aug. 4, 1966, Ser. No. 570,188 Claims priority, application Japan, Aug. 17, 1965, 40/ 67,527 8 Claims. (Cl. 200-19) ABSTRACT OF THE DISCLOSURE An ignition distributor for an internal combustion engine of the type in which spark advance is dependent upon the operating vacuum of the engine, and in which pressure responsive means producing a force depending on the aforementioned operating vacuum are connected to the turntable interrupter plate of the distributor to adjust the angular position of the latter, and in which the point of application of the force is shifted from a radially outer to a radially inner point on the plate during increase of the operating vacuum to obtain thereby an improved ignition point adjustment characteristic.

The present invention relates to an ignition distributor for internal combustion engines of the type in which spark advance is dependent upon the operating vacuum of the engine, and in which a pressure responsive means,

connected to the intake of the engine, is carried by the" interrupter housing and is connected by a rod to the interrupter plate mounted in the housing for turning the plate with respectsto the housing.

Known ignition distributors of this type are constructed in such a manner that the moment of ignition is adjusted proportional to the underpressure or vacuum in the intake of the combustion engine. In order to avoid knocking of the machine with an ignition time adjustment of the aforementioned kind, the adjustment is made only at a relatively high underpressure in the intake of the engine so that during low underpressure, for instance during full load, no adjustment of the ignition timing is carried out. This results in an incomplete combustion and thereby a reduced output of the engine.

It is an object of the present invention to overcome the aforementioned disadvantage and to provide an ignition distributor with an ignition time adjustment characteristic to increase the efficiency and the output of the internal combustion engine.

- With this object in view, the ignition distributor for internal combustion engines of the type in which spark advance is dependent upon the operating vacuum of the engine mainly comprises a distributor housing, a rotary engine driven cam in the housing, an interrupter plate mounted in the housing for angular movement with respect thereto, an interrupter carried by the plate and cooperating with the cam to be opened and closed during rotation of the latter, resilient means cooperating with the interrupter plate and being biased so as to yieldably maintain the plate in a starting position, pressure responsive means connected to the intake of the engine, and transmission means connecting the pressure responsive means to the plate for transmitting to the latter a turning moment depending on the vacuum applied to the pressure responsive means and to turn the plate against the force of the resilient means in a direction opposite to the direction of rotation of the cam, wherein the transmission means are constructed and arranged to reduce the turning moment transmitted to the plate from the pressure responsive means during increase of the vacuum in the engine intake.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a partially sectioned view of an ignition distributor according to the prior art with linear adjustment of the ignition time;

FIG. 2 is a diagram showing ignition time adjustment curves obtained with an ignition distributor according to the prior art and obtained with an ignition distributor according to the present invention;

FIG. 3 is a partially sectioned view of a first embodiment of an ignition distributor according to the present invention;

FIGS. 4 and 5 are partial views similar to FIG. 3 and showing the distributor illustrated in FIG, 3 in two adjusted positions;

FIG. 6 is a partially sectioned view of a second embodiment of a distributor according to the present invention; and

FIGS. 7 and 8 are partial views of the distributor according to FIG. 6 and showing the same in two adjusted positions.

In the various figures corresponding parts are designated with the same reference numerals.

Referring now to the drawings and more specifically to FIG. 1 of the same, in which a distributor according to the prior art is illustrated, it will be seen that this distributor mainly comprises a distributor housing 2 in which an engine driven cam 1 is turnably arranged which cooperates with a primary current interrupter 3 for opening and closing the latter during rotation of the cam 1. The interrupter 3 is mounted on an interrupter plate 4 arranged in the housing 2 for angular movement with respect thereto. A tension spring 5 is connected at opposite ends thereof to the interrupter housing and to the interrupter plate and the spring 5 is biased to yieldably hold the interrupter plate in a starting position. Connected to the interrupter housing 2 is a casing 6 through which a diaphragm 9 extends which defines in the casing 6 to the right side of the diaphragm 9, as viewed in FIG. 1, a pressure chamber which communicates through the conduit 7, only partly shown in FIG. 1, with the intake of the combustion engine in a known manner. A rod 8 is connected at one end to a central portion of the diaphragm 9, by being for instance riveted thereto, whereas the other end of the rod 8 is pivotally connected by means of a pin 10 to the interrupter plate 4.

When during the operation of the internal combustion engine the underpressure in the engine intake drops beyond a predetermined valve, the diaphragm 9 and the rod 8 connected thereto will be moved against the force exerted by the tension spring 5. Thereby the interrupter plate 4 is turned relative to the housing 2 in a direction opposite to the direction of rotation of the earn 1, whereby the moment of opening of the primary current interrupter 3, which determines the moment of ignition, is adjusted proportional to the underpressure in the engine intake. A linear adjustment characteristic of the ignition moment is obtained in this case, as illustrated by the dashed line in FIG. 2. In order to avoid the knocking region A of the engine during such an adjustment, the distributor is constructed in such a manner that the angular adjustment of the distributor plate will start only at an underpressure P At an underpressure which is smaller than P no adjustment of the moment of the ignition is carried out. In this region the engine will therefore operate with reduced efiiciency and the output of the engine will also be reduced.

FIGS. 35 illustrate a first embodiment of a distributor according to the present invention. The distributor illustrated in these three figures differs from the distributor according to the prior art shown in FIG. 1 in that the transmission means which transmits a force from the diaphragm 9 to the interrupter plate 4 include, besides the rod 8, a connecting member 11 pivotally connected at an outer end thereof by means of a pin 13 to the distributor housing 2. The end of the rod 8, opposite to the end connected to the diaphragm 9, is pivotally connected by means of a pin 10 to the connecting member 11 intermediate the ends of the latter. The connecting member 11 is formed intermediate the ends thereof with an opening 12 into which a first engaging pin 14 fixed to the interrupter plate 4 projects. The connecting member 11 is further provided with a radially inwardly projecting nose adapted to engage during pivotal movement of the connecting member 11 with a second engaging pin 15 fixed to and projecting upwardly from the interrupter plate 4 and arranged radially inwardly of the first engaging pin 14.

When during operation of the internal combustion engine the underpressure in the pressure chamber at the right side of the diaphragm 9, as viewed in FIG. 3, reaches a value P (FIG. 2), the membrane 9 will flex toward the right, as viewed in FIG. 3, against theforce produced by the spring and the rod 8 will thereby move in direction of the arrow shown in FIG. 3. The rod 8 turns thereby the connecting member 11 about its pivot, that is the pin 13. During the first part of this turning movement the interrupter plate will be turned in a direction opposite to the direction of rotation of the cam 1 due to the engagement of pin 14 with the left portion, as viewed in FIG. 3, of the face defining the opening 12 in the connecting member 11 (FIG. 3), to thereby adjust the moment of ignition (full line in FIG. 2). When the vacuum in the pressure chamber of the casing 6- increases and reaches the value P the nose on the connecting member 11 will engage the second engaging pin 15 and the point of force transmission between the connecting member 11 and the interrupter plate 4 will thereby be shifted from the radially outwardly located pin 14 to the radially inwardly located pin 15 (FIG. 4). Since the turning moment with which the interrupter plate 4 is turned relative to the housing 2 changes proportional to the underpressure and to the turning radius of the point of force application to the plate 4, the turning moment will be reduced during shifting of the point of force application from the pin 14 to the pin 15. However, since during the first part of the turning movement of the interrupter plate 4 the restoring moment of the tension spring 5 has been increased, a further increase of the underpressure will initially not result in further turning of the interrupter plate- 4. The restoring moment of the tension spring 5 will be again overcome only after the underpressure surpasses the value P and the adjustment of the interrupter plate will proceed proportional to the increase of the underpressure (FIG. 5 When the underpressure finally reaches the value P the rod 8 abuts against abutment means, not shown in the drawing, and the adjustment remains constant during further increase of the underpressure.

In the second embodiment illustrated in FIGS. 6-8, the connecting member 11 is pivotally mounted at its radially inner end on a pin 15' fixed to the interrupter plate 4. The connecting member 11 transmits the movement of the rod 8 to the interrupter plate 4 during adjustment of the ignition moment by turning the interrupter plate at an underpressure P first with a large turning radius when the connecting member 11 engages the interrupter plate 4 via the first engaging pin 14 (FIG. 6) and subsequently thereto, at an underpressure P the radially outwardly extending nose on the. connecting member 11' engages with the pin 13, so that the turning force is transmitted to plate 4 via the pivot pin 15' which is 10-.

cated radially inwardly of pin 14-, until at underpressure P; the rod 8 engages again with a non-illustrated abutment.

Any desired ignition moment adjusting line may be obtained by an appropriate selection of the distances between the turning axis of the interrupter plate 4 and the pins 14, 15, 10, and 13' or by arrangement of the relationship between the distances between the pins 13 and the pins 14, 15 and 10 in a predetermined manner. Thereby it is possible to obtain also at a small underpressure an adjustment of the moment of the ignition outside the knocking range of the internal combustion engine, whereby the efiiciency and the output of the engine is improved.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of ignition distributors for internal combustion engines differing from the types described above.

While the invention has been illustrated and described as embodied in an ignition distributor for an internal combustion engine of the type in which spark advance is dependent upon the operating. vacuum of the engine, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential charac teristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. An ignition distributor for an internal combustion engine of the type in which spark advance is dependent upon the operating vacuum of the engine comprising, in combination, a distribut'or housing; a rotary engine driven cam in said housing; an interrupter plate mounted in said housing for angular movement with: respect thereto about a turning. axis; an interrupter carried by said plate and cooperating with said cam to be opened and closed during rotation of the latter; resilient means cooperating with said interrupter plate and being biased so as to yieldably hold" the latter in a starting position; pressure responsive means connected to the intake of the engine and producing a force depending on the operating vacuum of the engine; and transmission means connecting said pressure responsive means to said plate for transmitting to the latter a turning moment depending on the force produced by said pressure responsive means and on the radial distance of the point of application of said force from said turning aXisso as to turn said plate against the force of the resilient means in a direction opposite to the direction of rotation of said cam and for shifting the point of application of said first mentioned force from a point spaced further from said turning axis to a point nearer to said turning axis during increase of the vacuum in the engine intake so as to reduce the turning moment transmitted to said plate from said pressure responsive means during increase of the vacuum in the engine intake.

2. An ignition distributor as set forth in claim 1, wherein said pressure responsive means includes a-pressure responsive: diaphragm, said transmission means being connected to said diaphragm.

3. An ignition distributor as set forth in claim 1, wherein said pressure responsive means includes a casing carried by said interrupter housing, a diaphragm extending transversely through said casing and defining with the latter a pressure chamber Which communicates With the engine intake, said transmission means being connected to said diaphragm.

4. An ignition distributor as set forth in claim 1, wherein said transmisssion means includes a connecting member, means connecting said pressure responsive means to said connecting member, a pair of radially outer engaging means respectively provide-d on said interrupter plate and said connecting member and engaging each other in a first angular position of said interrupter plate for connecting said connecting member to said plate, a pair of radially inner engaging means respectively provided on said interrupter plate and said connecting member for connecting the latter to said plate and being inactive in said first angular position of said plate, and means cooperating with said connecting member for disengaging said radially outer engaging means from each other and for rendering said radially inner engaging means active when said interrupter plate is moved by said transmission means during increase of the vacuum to a second angular position, said engaging means cooperating with said connecting member so as to reduce the turning moment transmitted by said transmisison means to said plate during increase of the vacuum in the engine intake.

5. An ignition distributor as set forth in claim 1, Wherein said transmission means includes a connecting member formed intermediate the ends thereof with an opening and with a radially inwardly projecting nose on one end, a pivot pin fixed to said housing and pivotally mounting said connecting member on the other end thereof, and a rod connected at one end to said pressure responsive means to be moved thereby in a given direction during increase of the vacuum in the engine intake and at the other end thereof pivotally connected to said connecting member intermediate the ends of the latter, a first engaging pin fixed to said interrupter plate and projecting through said opening, a second engaging pin fixed to said interrupter plate and arranged radially inwardly of said first engaging pin, said pins being arranged with respect to said opening and said nose in such a manner so that during a first part of the movement of said rod in said given direction said connecting member engages in the region of said opening said first pin so as to turn said plate in said opposite direction and so that during further movement of said rod in said given direction said nose of said connecting member engages with said second pin While said first pin becomes disengaged from said connecting member so that during said second part of the adjusting movement said transmission means will act with a smaller turning radius on the interrupter plate than during the first part of the adjusting movement.

6. An ignition distributor as set forth in claim 5, wherein said pressure responsive means includes a casing carried by said interrupter housing, a diaphragm extending transversely through said casing and defining with the latter a pressure chamber which communicates with the engine intake, said rod being connected to said diaphragm.

7. An ignition distributor as set forth in claim 1, wherein said transmission means includes a connecting mem ber formed With an opening intermediate its ends and With a radially outwardly projecting nose on one end, a pivot pin fixed to said interrupter plate and pivotally mounting said connecting member on the other end thereof, a rod connected at one end to said pressure responsive means to be moved thereby during increase of the vacuum in the engine intake in a given direction and at the other end thereof pivotally connected to said connecting member intermediate the ends of the latter, a first engaging pin fixed to said interrupter plate and projecting through said opening, and a second engaging pin fixed to said interrupter housing and located radially outwardly of said first engaging pin, said pins being arranged With respect to said opening and said nose in such a manner so that during a first part of the movement of said rod in said given direction said connecting member engages in the region of said opening said first pins so as to turn said plate in said opposite direction and so that during further movement of said rod in said given direction said nose of said connecting member engages with said second enga ing pin While said first engaging pin becomes disengaged from said connecting member so that during said second part of the adjusting movement said transmission means will act with a smaller turning radius on the interrupter plate than during the first part of the adjusting movement.

8. An ignition distributor as set forth in claim 7, wherein said pressure responsive means include a casing carried by said interrupter housing, a diaphragm extending transversely through said casing and defining with the latter a pressure chamber which communicates with the engine intake, said rod being connected to said diaphragm.

References Cited UNITED STATES PATENTS 3,262,777 9/1965 Scott 200-31 BERNARD A. GILHEANY, Primary Examiner. H. BROOME, Assistant Examiner. 

